iSlideRule Scales - D
"D" Scales
D
The D fundamental scale is normally positioned as the top scale on bottom rule. It runs from 1 to 10.

Gauge marks are located at C (√(4/π)), ⑫ (dozen), Ⓖ (gross), ρ (π/180), ρ'' (180*60*60)/π),  ρ' (180*60)/π), used in radians to degrees conversions, π, τ, ρ⁰ (180/π), and C1 (√(40/π)).

Formula: D = X
D1 The D1 scale is a ranged fundamental D scale, ranging from 1 to √10.

Gauge mark is present at √10.

Formula: D1 = √10 × X
D2 The D2 scale is a ranged reciprocal fundamental D scale, ranging from √10 to 1.

Gauge mark is present at √10.

Formula: D2 = 1 / ( √10 × X )
DF The DF scale, like the CF scale, is a folded D scale, with the fold at π.  It is found on the top or bottom rule, and is used for calculations involving π.

Gauge marks are located at π and τ.

Formula: DF = π × X
DF/m The DF/m scale is a folded D scale like the DF scale, with the fold is at 2.3 (natural log of 10).  This scale is useful when converting results between base 10 and base e.  This scale is usually located on the bottom rule, where the CF/m scale would be located on the slide.

Gauge marks are located at π and τ.

Formula: DF/m = ( loge 10 ) × X
DI
The DI scale is an inverse D scale, reversed in direction from the D scale (reciprocal scale).

Gauge marks are located at π and τ.

Formula: DI = 1 / X
DIF The DIF scale is another reciprocal folded fundamental scale, like the CIF scale.  This scale is normally on the top or bottom rule, and is folded at π, just like the CIF scale.

Gauge marks are located at π and τ.

Formula: DIF = 1 / ( π × X )

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